#include<bits/stdc++.h>
using namespace std;
int a[100],n,x;
void bbs(int l,int r,int value){
	if(l <= r){
		int mid = (l + r) / 2;
		if(a[mid] == value){
			cout << "yes" << endl;
			return ;
		}
		if(a[mid] < value) bbs(mid+1,r,value);
		else bbs(l,mid-1,value);
	}
	else{
		cout << "no" << endl ;
		return ;
	}
}
int main(){
	cin >> n;
	for(int i=1;i <= n;i++){
		cin >> a[i];
	}
	cin >> x;
	sort(a+1,a+1+n);
	bbs(1,n,x); 
	return 0;
}
